In the analysis of stated preferences studies, it is often assumed that protesting is a discretely measured item only occurring among those who are not willing to pay. However, various studies have recently shown that protest beliefs are as well held by respondents who state a positive willingness to pay (WTP). Using latent class (LC) models, we investigate the extent of heterogeneity with respect to protest beliefs among all respondents of two contingent valuation studies. The advantage of LC models is that classes of individuals are endogenously identified and no selection bias is introduced by ad hoc definitions of protesters. Further we investigate whether it is possible to identify a class of non-protesters. Finding a group of pure non-protesters could indicate how strongly stated WTP in the whole sample is affected by protest beliefs. For both samples, we find a class with strong protest beliefs but no pure non-protest class. Overall, our results suggest that LC models might not be the first choice to determine unbiased WTP measures, but they provide valuable insights into the degree of protesting expressed by different groups and corresponding determinants of group membership.